The present invention relates to a vehicle driving control system which is capable of suppressing vibration and, more particularly, to a vehicle driving control system which is suitable for improving the driving operability of the vehicle by suppressing vibration caused by the distortion of the drive shaft in a vehicle driven by a motor with a battery or an internal combustion engine.
In driving an electric vehicle, distortion of a drive shaft causes vibration during starting of the vehicle in some cases. The vibration is caused by distortion in the drive shaft and deformation in a supporting body placed between the driving force generating means, such as a motor, engine or the like, and the body of the vehicle.
Various methods of suppressing such a vibration are described in Japanese Patent Application Laid-Open No. 64-74005 (1989) and in the Transactions of the Japan Society of Mechanical Engineers (Series B) Vol. 53, No. 492 (August 1987) Paper No. 86-0514A. The former Publication discloses a method in which the vibration is decreased by controlling a torque command to oppose the vibration of the vehicle using the value of acceleration of the vehicle motor. The latter Publication discloses a method in which, to suppress a similar vibration in a vehicle driven by a diesel engine, a governor command (speed command) of the diesel engine is compensated using the difference between actual vehicle speed and a vehicle speed value calculated from the rotating speed of the diesel engine.
In the former method, since it is required to detect the acceleration of the motor from the speed of the motor, noise components in the detected value cause a problem. For example, when the acceleration is detected from the motor speed, a motor sensor capable of motor speed with a high accuracy and at a high speed is required, since the motor speed has to be determined by differential processing. On the other hand, although the latter method has an advantage in that there is no need to detect the motor acceleration, it requires detection of the actual vehicle acceleration and, therefore, required that a circuit for detecting the actual vehicle acceleration be added to the control unit. Further although a case of using a gearbox is described in the latter Publication, it is difficult to easily estimate how to apply that method to a case in which the actual vehicle speed is not used.